7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Deposition of Diamond-like Carbon Thin Filmson Silicon and Silicon Nitride
M. D. Ilasin, M. R. Vasquez Jr.,
Department of Mining, Metallurgical, and Materials Engineering, College of Engineering,
University of the Philippines Diliman, Quezon City, Philippines
e-mail: mdilasin@up.edu.ph
Diamond-like carbon (DLC) is a form of amorphous
carbon (C) with excellent mechanical and tribologicalproperties. It has superior mechanical properties similar
to diamond due to the large percentage of sp3 hybridized
C.[1,2] However, silicon nitride (Si3N4) is a refractorymaterial that has been extensively studied in both
tribological and high-temperature applications becauseof its high hardness, high-temperature strength, andchemical inertness attributed to its dense and highlyoriented covalent bonds.[3]In this study, a process for depositing DLC films as an
overcoat was developed using a custom-designed lowenergy ion source system (Figure 1). In addition, a radio
frequency (RF)-powered magnetron sputtering system
was used to deposit SiN films.

Figure 2. Raman spectrum deconvolution of DLC using
visible light illumination (532 nm).
Atomic force microscopy characterizations of the DLCon-Si3N4 bilayer showed very smooth surfaces with theroot-mean-square roughness equal to 0.46 nm.
A low-energy ion beam deposited DLC with a 70:30
Ar:N2 gas ratio on top of RF magnetron sputtered Si3N4
as a bilayer thin film offers the best balance ofmechanical and tribological properties. Using thecalculated deposition rates, we can control the overall
thickness to produce the desired dimensions. Thus, DLCSi3N4 bilayer thin film is a feasible overcoat for hard disk
drive media.

Figure 1. Schematic representation of the low-energy ion
source system.
The films were deposited on silicon (Si) substrates andthe effect of the deposition parameters such as the gas
precursor ratio of argon (Ar): acetylene (C2H2) (50:50
and 70:30), and the deposition time (5, 10, and 15 min)for DLC was investigated.
Raman spectral analysis revealed the successful
deposition of DLC thin films (Figure 2). It was also
observed that increasing the working gas content from
50:50 to 70:30 Ar:C2H2 gas ratio increased the ID/IG ratio.
Thus, between the two gas ratios, 70:30 Ar:C2H2 would
be the better admixture for a better DLC thin film. XRD
measurements confirmed the chemical identity andcrystal phase of the PVD-grown Si3N4 (401) thin films
which were deposited using a RF magnetron sputteringsystem.

This study was funded by the Department of Science andTechnology - Science Education Institute Engineering
Research and Development for Technology Graduate
Scholarship, DOST Philippine Council for Industry,
Energy and Emerging Technology Research andDevelopment (DOST-PCIEERD) Project No. 03058,
Commission on Higher Education Philippines-California
Advanced Research Institutes Project No. IIID 2016-007,and DOST-PCIEERD Project SPARCS.
References[1] J. Robertson. Progress in Solid State Chemistry(1991).
[2] J. Robertson. Properties of diamond-like carbon,Surface and Coatings Technology 50 (1992).
[3] B. K. Yen et al. Journal of Vacuum Science &Technology A: Vacuum, Surfaces, and Films 21 (2003).